Rules / canonical rules

canonical.single

Default

error

Plugin

canonical

A page has only one canonical link.

Why: With more than one canonical link, search engines may ignore all of them.

When off: pages with many canonical links pass.

<!-- ✗ Fails -->
<link rel="canonical" href="https://example.com/about/" />
<link rel="canonical" href="https://example.com/about-us/" />

<!-- ✓ Passes -->
<link rel="canonical" href="https://example.com/about/" />

References

• Google: How to specify a canonical URL: "Don't specify different URLs as canonical for the same page."